You can buy swimming jackets and air-filled tubes for your children if they are too fond of swimming and have not completed their swimming lessons yet. Any negligence can make you repay a lot. So never be negligent about your children especially when they are in the water.
Always keep watching. If you can't manage to be with them all the time, appoint any other person for your help. You can also browse to bandcaquatics.com to get more information about swimming classes in Toronto.
In case you have older children keep reminding them that swimming in deep water can be dangerous. They need to be careful while playing lest they incur a slip and fall in the water and fail to swim back.
Get an education about water safety yourself and then educate your family about it too. You must h learning the basic resuscitation techniques, and equipment. If by accident anybody has drowned in the water. First thing is to go after him and get him out of the water.
If the water is deep use a drain to empty the pool. Ask a friend to call an ambulance in the meanwhile. Once safely out of water lay him flat on the back and strike powerfully to force the water out of the mouth.
If it's a child hold his feet and hang him upside down now punch his back and belly to force water out of his body. Be gentle, so that you cause no injury to his vertebral column.